RASC1 : Detrained cloud water is calculated from the amount of evaporation at the top of convective cloud in original RAS.
RASC2 : Detrained cloud water is calculated from the amount of evaporation at the top of convective cloud in RAS version2 (RASV2). In RASV2, conversion of cloud water to convective rain in convection is parameterized as detailed.
Convection Schemes
RASC1 vs RASC2
RASC1 : Detrained cloud water is calculated from the amount of evaporation at the top of convective cloud in original RAS.
RASC2 : Detrained cloud water is calculated from the amount of evaporation at the top of convective cloud in RAS version2 (RASV2). In RASV2, conversion of cloud water to convective rain in convection is parameterized as detailed.
RASC2 may be more expensive than RASC1.
Moorthi, S., and M.J. Suarez, 1992: Relaxed Arakawa-Schubert. A Parameterization of Moist Convection for General Circulation Models. Mon. Wea. Rev., 120, 978–1002.
[Thanks to Aki for this part]